serial: 8250_dw: handle clock enable errors in runtime_resume

[ Upstream commit d312281 ]

Add error checking for clk_prepare_enable() calls in
dw8250_runtime_resume(). Currently if either clock fails to enable,
the function returns success while leaving clocks in inconsistent state.

This change implements comprehensive error handling by checking the return
values of both clk_prepare_enable() calls. If the second clock enable
operation fails after the first clock has already been successfully
enabled, the code now properly cleans up by disabling and unpreparing
the first clock before returning. The error code is then propagated to
the caller, ensuring that clock enable failures are properly reported
rather than being silently ignored.

Signed-off-by: Artem Shimko <a.shimko.dev@gmail.com>
Link: https://patch.msgid.link/20251104145433.2316165-2-a.shimko.dev@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>

Author: Artem Shimko

drivers/tty/serial/8250/8250_dw.c

@@ -738,11 +738,18 @@ static int dw8250_runtime_suspend(struct device *dev)
 
 static int dw8250_runtime_resume(struct device *dev)
 {
+	int ret;
 	struct dw8250_data *data = dev_get_drvdata(dev);
 
-	clk_prepare_enable(data->pclk);
+	ret = clk_prepare_enable(data->pclk);
+	if (ret)
+		return ret;
 
-	clk_prepare_enable(data->clk);
+	ret = clk_prepare_enable(data->clk);
+	if (ret) {
+		clk_disable_unprepare(data->pclk);
+		return ret;
+	}
 
 	return 0;
 }